JP2975843B2 - Monitor for length measurement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an object to improve a monitor for length measurement related to management of a processing dimension of a semiconductor device.

[0002]

2. Description of the Related Art A conventional length measuring monitor will be described below with reference to the drawings. In the manufacture of a semiconductor device, various patterns including wirings and contacts are formed, and it is necessary to know how these patterns are actually formed. For this purpose, it is a natural and reliable method to measure the pattern actually formed in the actual LSI. However, according to this method, the length must be measured for each individual LSI.
Since the number of length measurements becomes enormous, the work becomes very complicated.

Therefore, a simulated pattern which is similar to the pattern actually formed on the LSI is formed on a cut line (scribe line) between the LSI forming regions,
A method has been used in which the length of the dimension is measured to save labor. According to this method, it is sufficient to provide several (5 to 6) simulated patterns on one wafer and measure the length of the simulated pattern. Labor saving. Such a simulated pattern is called a monitor for length measurement. Usually, the shape of the monitor for length measurement was a single line shape as shown in FIG.

As an example, a description will be given below of a length measuring monitor for checking the diameter of a contact hole used for connection between wirings. In this case, as shown in FIG. 5, the length measuring monitor is formed on a scribe line 5 provided between the LSI forming regions 6 provided on the wafer 1 and has a single line shape. The contact hole monitor 4 includes a contact hole.

A method of forming the contact hole monitor 4 will be described below together with a length measuring method using the same. First, the insulating film 2 is formed on the LSI forming region 6 and the scribe lines 5 in a process of manufacturing an LSI formed in the LSI forming region 6. Next, in the step of forming a resist pattern serving as an etching mask when forming a contact hole in the LSI, the contact hole and the resist pattern are simultaneously formed.
A resist monitor 3, which is a resist pattern having an opening in a region where the monitor 4 is formed, is formed on the insulating film 2 (FIG. 6), and its diameter is measured by a SEM (Scanning E).
(electronMicroscope: scanning electron microscope).

Next, in the step of forming the contact hole by etching the insulating film 2 using the resist pattern as a mask in the LSI, at the same time, the insulating film 2 is dry-etched using the resist monitor 3 as a mask to form a contact hole. The monitor 4 is formed (FIG. 7). Thereafter, the resist monitor 3 is removed using plasma ashing and an organic solvent or the like, and the diameter of the contact hole monitor 4 is measured by a length measuring SEM (FIG. 8). FIG.
Is a sectional view taken along line AA of FIG.

In this way, by measuring the diameter of the resist monitor 3, the opening size of the resist pattern inside the LSI can be obtained, and by measuring the diameter of the contact hole monitor 4, the contact hole inside the LSI can be measured. This is the same as the diameter obtained, and it is also known whether there is such a difference between the dimension of the resist pattern and the diameter of the contact hole formed based thereon.

[0008]

However, a large number of contact holes are formed in an actual LSI such as a memory cell.
Since it is formed by a single line, in the lithography process, the light is diffracted and interfered by an adjacent pattern to change the exposure state, and in the dry etching process, carbon atoms scattered from the resist pattern serving as a mask. [C] affects the etching state of the adjacent pattern.
As in the loading effect and the like, it is not possible to reflect on the monitor the interaction caused by the proximity of the actual pattern, so that there is a considerable disparity with the actual pattern inside the LSI, which does not fit the actual situation.

In particular, the difference relatively increases with miniaturization, and becomes a difference that cannot be ignored in products at the submicron level, so that the actual pattern must be measured. On the other hand, if the length is measured using an actual pattern, a program for controlling the length measurement SEM must be created for each pattern of each chip on the wafer, and the program file becomes enormous. Also,
As the number of program files increases, there have been problems such as an increase in creation time and an increase in work complexity.

[0010]

In order to solve the above problem, as shown in FIGS. 1 to 5, a plurality of contact holes formed on a scribe line and corresponding to an actual pattern are arranged in a matrix. By using the length measuring monitor, it is possible to obtain a monitor reflecting the actual pattern state of the semiconductor device.

A plurality of contact holes formed in a scribe line and arranged in a matrix corresponding to a dense state of an actual pattern, and a plurality of contact holes formed in the scribe line at a position distant from the plurality of contact holes, By using a length measurement monitor including a single contact hole corresponding to the sparse state, it is possible to obtain a monitor reflecting the dense state and the sparse state of the actual pattern of the semiconductor device.

[0012]

According to the monitor for length measurement according to the present invention, as shown in FIG. 1, a monitor for length measurement in which a plurality of contact holes are arranged in a matrix in place of a monitor of a single line arranged on a scribe line. Since a monitor is used, it is possible to simulate conditions very close to an actual pattern, for example, a memory cell in which a large number of close contact holes are arranged. Proximity effects in the lithography process and micro-
It is possible to obtain a monitor reflecting the loading effect.

Furthermore, since a single contact hole corresponding to the sparse state of the actual pattern is provided at a position distant from the plurality of contact holes, for example, the periphery of the memory cell region where the contact holes are sparsely arranged. A pattern such as a circuit or an ASIC can be reproduced in a pseudo manner, and a monitor corresponding to the pattern having a small proximity effect or the like can be obtained. The measurement result of the monitor and the plurality of contact holes are arranged in a matrix. By comparing the length measurement result of the length measurement monitor arranged in the above, it is possible to know how much the diameter of the contact hole changes due to the proximity effect or the like.

Further, according to the monitor for length measurement according to the present invention, a monitor having a very small difference from the actual pattern of the LSI can be obtained even if the miniaturization progresses. Improved, without having to measure the actual pattern directly. Therefore, it is not necessary to create a program for controlling the length measurement SEM for each pattern of each chip on the wafer as compared with a case where an actual pattern is directly measured, so that the program size can be significantly reduced. In addition, it is possible to suppress an increase in program file creation time caused by an increase in the program size and a complicated length measurement operation accompanying the increase in the program file creation time.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A length measuring monitor according to an embodiment of the present invention will be described below with reference to the drawings. The length measuring monitor described in this embodiment is formed on a scribe line 15 provided between LSI forming regions 16 provided on a wafer 11 as shown in FIG. 25 contact holes of minimum diameter arranged in a × 5 row,
This is a contact hole monitor consisting of a single contact hole having a minimum diameter disposed at a distance of 5 to 150 μm from the 25 contact holes.

The forming method will be described below together with a length measuring method using the contact hole monitor 14. First, in a manufacturing process of an LSI formed in the LSI formation region 16, the LSI formation region 16 and the scribe line 1 are formed.
An insulating film 12 is formed on 5. Next, in the step of forming a resist pattern serving as an etching mask when forming a contact hole in the LSI, the resist monitor 13, which is a resist pattern having an opening in a region where a contact hole monitor 14 is formed at the same time, It is formed on the film 12 (FIG. 2), and the diameter of one of the openings is measured by a length measurement SEM.

Next, in the step of forming a contact hole by etching the insulating film 12 using a resist pattern as a mask in the LSI, a resist monitor 13 is simultaneously formed.
Is used as a mask to dry-etch the insulating film 12 to form a contact hole monitor 14 (FIG. 3). Thereafter, the resist monitor 13 is removed using plasma ashing and an organic solvent, and the diameter of the contact hole monitor 14 is measured by a length measuring SEM (FIG. 4). FIG. 4 is a sectional view taken along line XX of FIG.

By measuring the diameter of the resist monitor 13 in this way, the opening size of the resist pattern inside the LSI can be obtained, and the contact hole monitor 1
By measuring the diameter of No. 4, the diameter of the contact hole inside the LSI is the same as that obtained, and further,
It can also be seen whether there is such a difference between the size of the resist pattern and the diameter of the contact hole formed based on the size.

As described above, according to the monitor for length measurement according to the present invention, the monitor for length measurement in which a plurality of contact holes are arranged in a matrix, instead of the monitor of a single line arranged in a scribe line. Is used, it is possible to simulate a condition very close to the actual pattern, for example, a memory cell in which a large number of close contact holes are arranged. It is possible to obtain a monitor reflecting the proximity effect of the lithography process and the micro-loading effect of the etching process, which are caused by the interaction of.

Further, since a single contact hole corresponding to the sparse state of the actual pattern is provided at a position distant from the plurality of contact holes, for example, around the memory cell region where the contact holes are sparsely arranged. A pattern such as a circuit or an ASIC can be reproduced in a pseudo manner, and a monitor corresponding to the pattern having a small proximity effect or the like can be obtained. The measurement result of the monitor and the plurality of contact holes are arranged in a matrix. By comparing the length measurement result of the length measurement monitor arranged in the above, it is possible to know how much the diameter of the contact hole changes due to the proximity effect or the like. The single contact hole is provided at a position away from the plurality of contact holes in order to eliminate a proximity effect or the like between the two.

Further, according to the monitor for length measurement according to the present invention, a monitor having a very small difference from the actual pattern of the LSI can be obtained even if the miniaturization progresses. Improved, without having to measure the actual pattern directly. Therefore, it is not necessary to create a program for controlling the length measurement SEM for each pattern of each chip on the wafer as compared with a case where an actual pattern is directly measured, so that the program size can be significantly reduced. In addition, it is possible to suppress an increase in program file creation time caused by an increase in the program size and a complicated length measurement operation accompanying the increase in the program file creation time.

Experimental results for explaining the operation and effect of the length measuring monitor of this embodiment are shown below. Table 1 is a table in which the measurement results of the conventional single-line length measuring monitor and the measurement results of the length measuring monitor of the present embodiment are compared and compared. For the length measuring monitor of this embodiment, 5 rows corresponding to the dense state of the actual pattern.
The measurement results of 25 contact holes arranged in five rows and a single contact hole corresponding to the sparse state of the actual pattern are shown.

[0023]

[Table 1]

In Table 1, PE is the aperture value of a plurality of contact hole monitors (usually provided at the center, upper, lower, left, and right points of the wafer) provided in the wafer. And PER is the difference between the maximum value and the minimum value of the aperture values of the plurality of contact hole monitors. PR is the average value of the aperture values of a plurality of resist monitors provided in the wafer, and PRR is the difference between the maximum value and the minimum value of the aperture values of the contact hole monitors. It is.

Further, the CD loss is the difference between PR and PE, and is the size of the opening of the resist monitor and the contact hole monitor formed by etching using the resist monitor as a mask. The difference from the dimensions is shown. C
Regarding D loss, in this experiment, as shown in Table 1,
0.06 between the conventional monitor and the monitor of the present embodiment.
There is a difference of ~ 0.07 μm, and at the submicron level,
This is a negligible difference, and the reliability of the conventional monitor is significantly reduced. Further, comparing the PER and PRR of the monitor of the present embodiment with the monitor of the present embodiment, the monitor of the present embodiment shows a smaller value in both cases. It was confirmed that the monitor was closer to the actual pattern and higher in reliability than-.

Further, the length measuring monitor of the present embodiment, 25 contact holes arranged in 5 rows × 5 columns corresponding to the dense state of the actual pattern, and the sparseness of the actual pattern. Comparing the measurement results of a single contact hole corresponding to the state, there is a difference of 0.009 μm in CD loss, 0.016 μm in PER, and 0.002 μm in PRR. This is due to the proximity effect in the lithography process due to the density of the pattern and the micro-row in the etching process.
This is considered to reflect the difference in the loading effect.

[0027]

As described above, according to the length measuring monitor according to the present invention, since a plurality of contact holes are arranged in a matrix, the length measuring monitor is used. Like a memory cell in which holes are arranged, conditions very close to the actual pattern can be reproduced in a pseudo manner, and the difference from the actual pattern is small, reflecting the actual pattern state of the LSI. Since a monitor can be obtained, the reliability of the measurement result is improved, and it is not necessary to directly measure an actual pattern.

Further, since a single contact hole corresponding to the sparse state of the actual pattern is provided at a position distant from the plurality of contact holes, for example, around the memory cell region where the contact holes are sparsely arranged. A pattern of a circuit, an ASIC, or the like can be reproduced in a pseudo manner, a difference from the actual pattern is small, and a monitor reflecting the actual pattern state of the LSI can be obtained.

Further, by comparing the length measurement result of the monitor of the single contact hole with the length measurement result of the length measurement monitor in which the plurality of contact holes are arranged in a matrix, the proximity effect or the like is obtained. It is also possible to know how much the diameter of the contact hole changes.
Furthermore, as compared to the case where the actual pattern is directly measured, the length measurement SE for each chip pattern on the wafer is used.
Since it is not necessary to create a program for controlling M, the size of the program can be significantly reduced, the time required to create a program file has been increased due to the increase in the program size, and the length measurement work involved has been complicated. And so on.

[Brief description of the drawings]

FIG. 1 is a top view for explaining a length measuring monitor according to an embodiment of the present invention.

FIG. 2 is a first cross-sectional view for explaining a method of manufacturing the length measuring monitor according to the embodiment of the present invention.

FIG. 3 is a second cross-sectional view for explaining the method of manufacturing the length measuring monitor according to the embodiment of the present invention.

FIG. 4 is a third sectional view for explaining the method of manufacturing the length measuring monitor according to the embodiment of the present invention.

FIG. 5 is a top view illustrating a length measuring monitor according to a conventional example.

FIG. 6 is a first cross-sectional view for explaining a method of manufacturing a length measuring monitor according to a conventional example.

FIG. 7 is a second cross-sectional view illustrating a method of manufacturing a length measuring monitor according to a conventional example.

FIG. 8 is a third cross-sectional view illustrating a method of manufacturing a length measuring monitor according to a conventional example.

Claims (3)

(57) [Claims] 1. A scriber between LSI forming regions.
A plurality of contact holes corresponding to an actual pattern of an LSI are formed in a matrix and are arranged in a matrix. 2. A scriber between LSI forming regions.
A plurality of contact holes having a minimum diameter corresponding to an actual LSI pattern are arranged in a matrix. 3. A scriber between LSI formation regions.
A plurality of contact holes formed on the scribe line and arranged in a matrix corresponding to a dense state of the actual pattern of the LSI; and a plurality of contact holes formed on the scribe line at a position apart from the plurality of contact holes. A length measurement monitor comprising a single contact hole corresponding to a sparse state.